1. Field of the Invention:
Combined heat-pump and furnace systems with controls for optimizing operating efficiency.
2. Description of the Prior Art:
U.S. Pat. No. 3,996,998 (Garst et al) shows a system of a type generally similar to the present invention. The disadvantage inherent in the Garst et al control is that the heat pump and the furnace are each operated along during the heating phase. When the furnace is activated under load conditions which preclude the heat pump from satisfying the load, the heat pump is simultaneously de-energized. Since it takes a period of time for the furnace to begin delivering warm air to the enclosure, cool air is supplied during this interim period causing discomfort to the occupants inside the controlled space.